Voltage stabilized power supply with capacitor isolation during supply voltage variations

• US 5,243,271 A
• Filed: 12/05/1991
• Issued: 09/07/1993
• Est. Priority Date: 12/11/1990
• Status: Expired due to Fees

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Lommers, Anthonius J. J. C.
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): BERHANE, ADOLF D
• Application Number:
  US07/804,267
• Time in Patent Office: 642 Days
• Field of Search: 323/313, 323/281, 323/273, 323/274, 323/314, 323/315, 323/284, 323/299, 323/288, 323/279
• US Class Current: 323/279
• CPC Class Codes: G05F 1/56 using semiconductor devices in series with the load as final control devices G05F1/461 takes precedence

Abstract

A power-supply arrangement comprises a reference circuit for generating a reference voltage (Vref). The reference circuit is coupled between a first (1) and a second (2) supply voltage terminal for receiving a supply voltage. A stabilizing circuit (4) generates a stabilization voltage (Vstab) related to the reference voltage and has an input terminal for receiving the reference voltage, a common terminal (7), and an output terminal for supplying the stabilization voltage. A switching stage (10) is switched depending on the supply voltage and comprises at least one switching element coupled between the input terminal and the common terminal. A current source is switched depending on the supply voltage and is coupled between the second supply voltage terminal and the common terminal. A capacitor is coupled between the common terminal and the first supply voltage terminal, and a buffer stage is coupled between the common terminal and the output terminal.

Claims

1. A power-supply arrangement comprising a reference circuit for generating a reference voltage, said reference circuit having a reference terminal for supplying the reference voltage, the reference circuit being coupled between a first and a second supply voltage terminal for receiving a supply voltage, and a stabilising circuit for generating a stabilisation voltage related to the reference voltage which stabilising circuit has an input terminal, coupled to the reference terminal for receiving the reference voltage, a common terminal and an output terminal, for supplying the stabilisation voltage, the common terminal being coupled to the first supply voltage terminal by means of a capacitor, wherein the stabilising circuit further comprises a switching stage which is switched in dependence upon the supply voltage and which comprises at least one switching element coupled between the input terminal and the common terminal, and a buffer stage coupled between the common terminal and the output terminal.

2. A power-supply arrangement as claimed in claim 1, wherein the stabilising circuit further comprises a current source which is switched dependent upon the supply voltage and which is coupled between the second supply voltage terminal and the common terminal.

3. A power-supply arrangement as claimed in claim 2, wherein the stabilising circuit further comprises a driver circuit for driving the switching stage and the switched current source dependent upon the supply voltage.

4. A power-supply arrangement as claimed in claim 3, wherein the reference circuit comprises at least one impedance coupled between the reference terminal and the first supply voltage terminal, and the switching stage further comprises a further current source which is switched dependent upon the supply voltage and which is coupled between the second supply voltage terminal and the input terminal, the switching element comprising a transistor having a base coupled to the input terminal, having a collector coupled to the first supply voltage terminal, and having an emitter coupled to the common terminal.

5. A power-supply arrangement as claimed in claim 4, wherein the driver stage comprises a differential pair, having a first input coupled to a terminal for receiving a measure of the supply voltage, a second input coupled to the output terminal, a first output adapted to drive the switched current source, and a second output adapted to drive the further switched current source.

6. A power-supply arrangement as claimed in claim 5, wherein the first output of the differential pair is coupled to an input of a current mirror, the switched current source being an output of said current mirror.

7. A power-supply arrangement as claimed in claim 6, wherein the second output of the differential pair is coupled to an input of a further current mirror, the further switched current source being an output of said further current mirror.

8. A power-supply arrangement as claimed in claim 1, wherein the buffer stage comprises a transistor having a base coupled to the common terminal, having a collector coupled to the second supply voltage terminal, and having an emitter coupled to the output terminal.

9. A power-supply arrangement as claimed in claim 2, wherein the buffer stage comprises a transistor having a base coupled to the common terminal, having a collector coupled to the second supply voltage terminal, and having an emitter coupled to the output terminal.

10. A power-supply arrangement as claimed in claim 3, wherein the buffer stage comprises a transistor having a base coupled to the common terminal, having a collector coupled to the second supply voltage terminal, and having an emitter coupled to the output terminal.

11. A power-supply arrangement as claimed in claim 4, wherein the buffer stage comprises a transistor having a base coupled to the common terminal, having a collector coupled to the second supply voltage terminal, and having an emitter coupled to the output terminal.

12. A power-supply arrangement as claimed in claim 1 wherein the stabilizing circuit further comprises a switchable current source switchable as a function of the supply voltage and coupled between one of said supply voltage terminals and the capacitor.

13. A voltage stabilized power supply comprising:

first and second supply voltage terminals,

a reference voltage circuit coupled between said first and second supply voltage terminals and having a reference terminal that produces a reference voltage, and

a voltage stabilizing circuit for generating at its output terminal a stabilization voltage related to the reference voltage, said voltage stabilizing circuit having an input terminal coupled to the reference terminal, a common terminal coupled to the input terminal via a semiconductor switching element which is switched as a function of the supply voltage, a capacitor coupled between the common terminal and the first supply voltage terminal, and a semiconductor buffer stage coupled between the common terminal and the output terminal.

14. A voltage stabilized power supply as claimed in claim 13, wherein the voltage stabilizing circuit further comprises a switchable current source switchable as a function of the supply voltage and coupled between the second supply voltage terminal and the common terminal.

15. A voltage stabilized power supply as claimed in claim 14, wherein a given variation of the supply voltage from a nominal value opens said semiconductor element and said switchable current source thereby to isolate the capacitor from the current source and from the reference voltage.

16. A voltage stabilized power supply as claimed in claim 14, wherein the voltage stabilizing circuit further comprises a second switchable current source switchable as a function of the supply voltage and coupled between the second supply voltage terminal and the input terminal, said first switchable current source being closed when the second switchable current source is open and vice versa.

17. A voltage stabilized power supply as claimed in claim 13, wherein the semiconductor switching element is connected with its emitter/base circuit coupled between the common terminal and the input terminal, and said semiconductor buffer stage comprises an emitter follower transistor with its base/emitter circuit coupled between the common terminal and the output terminal whereby temperature compensation is provided by the emitter follower transistor and the semiconductor switching element.

18. A voltage stabilized power supply as claimed in claim 16, wherein the voltage stabilizing circuit further comprises a transistor differential amplifier driver stage having a first input which receives a voltage determined by the supply voltage, a second input coupled to the output terminal, and first and second outputs coupled to first and second current mirror circuits, respectively, which comprise parts of the first and second switchable current sources, respectively.

19. A voltage stabilized power supply as claimed in claim 16, wherein the reference voltage circuit comprises a further current source and at least one impedance element serially connected between the second and first supply voltage terminals and with a node therebetween connected to said reference terminal.

20. A voltage stabilized power supply as claimed in claim 13, wherein said voltage supply terminals are adapted to be connected to terminals of at least one electric battery.

21. A voltage stabilized power-supply as claimed in claim 13 further comprising a switching transistor switchable as a function of the supply voltage and coupled between the second supply voltage terminal and the common terminal so as to operate as a switchable current source for the capacitor.